1. Field of the Invention
The present invention relates to a dust and moisture free switch and, particularly, to a switch, which has an isolation part disposed between a control plate and a casing to prevent the dust or the moisture from disturbing the contact pole device at the bottom of the casing.
2. Description of Related Art
It is known that the switch has been used for years in the field of power supply as a required device for controlling the power on or off and avoiding accidents caused by continuing supplying the power. The switch usually can be classified into a constant on switch, which is off at the time of the current being not taken, and a constant off switch, which is on at the time of the current being taken. Thus, products powered by the electricity have provided with a switch and the basic principle for operating a switch is in that two electric poles are utilized to connect with each other as a close circuit for constituting a state of current taking and the two electric poles disconnect from each other as an open circuit to form a state of current not taking.
Generally, safety is also an important factor has to be considered in addition to an accurate operation of power on or power off. For instance, the switch has to be not leakage of electricity and not incorrect connection. Besides, the switch has to be free from dust or moisture in special locations such as a working environment with floating powder dust or heavy moisture such that it can prevent the contact pole device in the switch from short circuit or corrosion and prolong the life span of the switch. Currently, a treatment with regard to anti-dust or anti-moisture is done with a soft cover being attached to the top of the switch and a projecting rectangular frame enclosing the control plate thereof so as to conceal the switch at the top thereof. However, the efficiency of the wrap up type switch is in that both arc ends of the control plate just corresponds to both end edges of the rectangular frame so that it has to overcome a resistance force at each end edge due to the rectangular frame having a height during an operation of pressing and it is hard to operate smoothly. Besides, the wrap up type switch at the rectangular frame thereof is easy to result in breaking because of being repeatedly pressed and lose the function of ant-dust or anti-moisture.
The crux of the present invention is to provide a dust and moisture free switch, which includes a hollow casing, a contact pole device, a control plate and an isolation part. The contact pole device is inserted to the bottom of the casing with a stationary pole and a support pole being inserted into and locating at a respective pole hole and an arc pole being attached to the top of the support pole such that the arc pole can swing leftward and rightward. The control plate is joined to the upper portion of the casing and has the bottom thereof being arranged with a central hollow post to fit with an extensible stir lever, which has a bottom thereof contacting with the arc pole. The isolation part is made of soft high molecular plastic material and passed through by and fitting with the stir lever so as to be located at and closely joined to the inner wall of the casing to perform a function of blocking dust or moisture to enter the bottom of the casing. The stir lever can slide on the arc pole in case of an end of the control plate being pressed such that the arc pole can touch or detach from the stationary pole selectively to perform power on or off.